This isn`t that easy! I have a lot of favourites.
I`ll try to list and explain why I like it.
Microgaming
100 lines:
Summer Holiday (I would like a free spin option on this)
Cashapillar
Alaskan Fishing
All these three mentioned have stacked wilds.
30 lines
Cashanova (the bonus game)
Deck the halls (stacked santas and wilds in free spin)
Tomb Raider - secret of the swords (the bonus games)
25 lines
Flight Zone (stacked wilds + the bonus game)
Magic Spell (the bonus game)
20 lines
Franken Cash (The picking bonus game could have been boring but it`s fun)
Snow Honeys (same as the above)
Wealth Spa (the opportunity to save and choose bonus game)
Jonny Specter (a one of a kind game)
15 lines
Hitman (many cool things and just 15 lines)
9 lines
Witches Wealth (bonus game)
Sneak a Peek-Doctor Doctor (several cool features)
Alley Cats (I like dog bowling)
RTG
Coyote Cash (a coyote blowing his head off with a gun is fun, 25 free games too)
Diamond Dozen (Ilike the multiplier if the diamonds)
Green Light (bonus game)
Goldbeard (stacked wilds)
Hidden Riches (the bonus game is good, unfortunately only 5 free spins)
Honey to the bee (I like the look of it and the wilds are nice to look at)
Naughty or Nice (look at it and you see why I like it)
Outta this world (expanding wilds and a fun picking game)
Rudolphs Revenge (really good looking)
T-Rex (a funny dangerous dinosaur)
Warlock`s spell (bonus game)
Triple Twister (A huge expanding wild/twister)
Realms of Riches (retriggering stuff is fun)
I will come back later with slots from other software producers.